func nextAtom(sr *io.SectionReader) (string, *io.SectionReader, error) {
var asz uint32
var sz int64
atyp := make([]byte, 4)
if err := binary.Read(sr, binary.BigEndian, &asz); err != nil {
return "", nil, err
}
if asz == 0 {
// Size is entire section
sz = sr.Size()
} else if asz == 1 {
return "", nil, ErrNotImplemented
} else {
sz = int64(asz)
}
if _, err := io.ReadFull(sr, atyp); err != nil {
return "", nil, err
}
sz = sz - 8 // 4 bytes for size, 4 bytes for type
// Get current offset
cur, err := seekCur(sr)
if err != nil {
return "", nil, err
}
// Consume remainder of parent
if _, err := io.CopyN(ioutil.Discard, sr, sz); err != nil {
return "", nil, err
}
return string(atyp), io.NewSectionReader(sr, cur, sz), nil
}
func readCompressed(r *io.SectionReader, offset int64, s []byte) (int, error) {
zr, err := zlib.NewReader(io.NewSectionReader(r, offset, r.Size()-offset))
if err != nil {
return 0, err
}
return io.ReadFull(zr, s)
}
func readVarint(r *io.SectionReader, offset int64) (v int64, n int, err error) {
var buf [16]byte // 109 bits should be enough for everybody.
_, err = r.ReadAt(buf[:], offset)
if err == io.EOF || err == io.ErrUnexpectedEOF {
err = nil
}
if err != nil {
return
}
u, n := binary.Uvarint(buf[:])
v = int64(u)
return
}
func readStringPool(sr *io.SectionReader) (*ResStringPool, error) {
sp := new(ResStringPool)
if err := binary.Read(sr, binary.LittleEndian, &sp.Header); err != nil {
return nil, err
}
stringStarts := make([]uint32, sp.Header.StringCount)
if err := binary.Read(sr, binary.LittleEndian, stringStarts); err != nil {
return nil, err
}
styleStarts := make([]uint32, sp.Header.StyleCount)
if err := binary.Read(sr, binary.LittleEndian, styleStarts); err != nil {
return nil, err
}
sp.Strings = make([]string, sp.Header.StringCount)
for i, start := range stringStarts {
var str string
var err error
sr.Seek(int64(sp.Header.StringStart+start), os.SEEK_SET)
if (sp.Header.Flags & UTF8_FLAG) == 0 {
str, err = readUTF16(sr)
} else {
str, err = readUTF8(sr)
}
if err != nil {
return nil, err
}
sp.Strings[i] = str
}
sp.Styles = make([]string, sp.Header.StyleCount)
for i, start := range styleStarts {
var str string
var err error
sr.Seek(int64(sp.Header.StylesStart+start), os.SEEK_SET)
if (sp.Header.Flags & UTF8_FLAG) == 0 {
str, err = readUTF16(sr)
} else {
str, err = readUTF8(sr)
}
if err != nil {
return nil, err
}
sp.Styles[i] = str
}
return sp, nil
}
func (pk *PackReader) checkIdxMagic(idx *io.SectionReader) (err error) {
var buf [idxHeaderSize]byte
_, err = idx.ReadAt(buf[:], 0)
if err != nil {
return
}
magic := [4]byte{buf[0], buf[1], buf[2], buf[3]}
if magic != ([4]byte{'\xff', 't', 'O', 'c'}) {
return errBadIdxMagic
}
for i := range pk.idxFanout {
pk.idxFanout[i] = binary.BigEndian.Uint32(buf[8+4*i:])
}
return nil
}
func checkPackMagic(pack *io.SectionReader) (version, count uint32, err error) {
var buf [12]byte
_, err = pack.ReadAt(buf[:], 0)
if err != nil {
return
}
magic := [4]byte{buf[0], buf[1], buf[2], buf[3]}
if magic != ([4]byte{'P', 'A', 'C', 'K'}) {
err = errBadPackMagic
}
version = binary.BigEndian.Uint32(buf[4:8])
if version != 2 {
err = errUnsupportedPackVersion
}
count = binary.BigEndian.Uint32(buf[4:8])
return
}
/*ParsePackHeader A header appears at the beginning and consists of the following:
4-byte signature:
The signature is: {'P', 'A', 'C', 'K'}
4-byte version number (network byte order):
Git currently accepts version number 2 or 3 but
generates version 2 only.
4-byte number of objects contained in the pack (network byte order)
Observation: we cannot have more than 4G versions ;-) and
more than 4G objects in a pack.
*/
func ParsePackHeader(pack *io.SectionReader) (version, objectCount uint32, err error) {
buf := make([]byte, 12)
_, err = pack.Read(buf)
if err != nil {
return
}
if signature := string(buf[:4]); signature != packSignature {
err = errors.New("pack header has wrong signature: " + signature)
return
}
version = binary.BigEndian.Uint32(buf[4:8])
if version != 2 {
err = fmt.Errorf("version unsupport: %d ", version)
return
}
objectCount = binary.BigEndian.Uint32(buf[8:])
return
}
// readVaroffset reads the pseudo-varint used to encode offsets for delta bases.
// It is a big-endian form: 1|a0, ..., 1|a_{n-1}, 0|a_n.
// representing:
// (a0+1)<<7*n + ... + (a_{n-1}+1)<<7 + a_n
func readVaroffset(r *io.SectionReader, offset int64) (v int64, n int, err error) {
var buf [16]byte // 109 bits should be enough for everybody.
n, err = r.ReadAt(buf[:], offset)
if err == io.EOF || err == io.ErrUnexpectedEOF {
err = nil
}
if err != nil {
return
}
u := uint64(0)
for i, b := range buf[:n] {
if i > 0 {
u++
}
u <<= 7
u |= uint64(b &^ 0x80)
if b&0x80 == 0 {
return int64(u), i + 1, nil
}
}
return int64(u), len(buf), io.ErrUnexpectedEOF
}
//InflateZlib unbuffered io
func InflateZlib(r *io.SectionReader, len int) (bs []byte, err error) {
var out bytes.Buffer
br := bufio.NewReader(r)
zr, err := zlib.NewReader(br)
if err != nil {
return
}
defer zr.Close()
_, err = io.Copy(&out, zr)
if err != nil {
return
}
if out.Len() != len {
return nil, fmt.Errorf("inflated size mismatch, expected %d, got %d", len, out.Len())
}
bs = out.Bytes()
_, err = r.Seek(0-int64(br.Buffered()), 1)
if err != nil {
return
}
return
}
// newDecryptionReader returns an authenticated, decryption reader
func newDecryptionReader(r *io.SectionReader, f *File) (io.Reader, error) {
keyLen := aesKeyLen(f.aesStrength)
saltLen := keyLen / 2 // salt is half of key len
if saltLen == 0 {
return nil, ErrDecryption
}
// grab the salt and pwvv
saltpwvv := make([]byte, saltLen+2)
if _, err := r.Read(saltpwvv); err != nil {
return nil, err
}
salt := saltpwvv[:saltLen]
pwvv := saltpwvv[saltLen : saltLen+2]
// generate keys only if we have a password
if f.password == nil {
return nil, ErrPassword
}
decKey, authKey, pwv := generateKeys(f.password(), salt, keyLen)
if !checkPasswordVerification(pwv, pwvv) {
return nil, ErrPassword
}
dataOff := int64(saltLen + 2)
dataLen := int64(f.CompressedSize64 - uint64(saltLen) - 2 - 10)
// // TODO(alex): Should the compressed sizes be fixed?
// // Not the ideal place to do this.
// f.CompressedSize64 = uint64(dataLen)
// f.CompressedSize = uint32(dataLen)
data := io.NewSectionReader(r, dataOff, dataLen)
authOff := dataOff + dataLen
authcode := io.NewSectionReader(r, authOff, 10)
ar := newAuthReader(authKey, data, authcode, f.DeferAuth)
dr := decryptStream(decKey, ar)
if dr == nil {
return nil, ErrDecryption
}
return dr, nil
}
func cmapParser(_ SFNT, r *io.SectionReader) Table {
t := new(Cmap)
header := CmapHeader{}
if err := binary.Read(r, binary.BigEndian, &header); err != nil {
return nil
}
t.Version = header.Version
numTables := header.NumTables
encodingRecord := make([]EncodingRecord, numTables)
if err := binary.Read(r, binary.BigEndian, encodingRecord); err != nil {
return nil
}
t.Subtable = make([]CmapSubtable, numTables)
for i, v := range encodingRecord {
pid, eid, offset := v.PlatformID, v.EncodingID, int64(v.Offset)
format := make([]byte, 8)
r.ReadAt(format, offset)
var length int64
switch binary.BigEndian.Uint16(format[:2]) {
case 0, 2, 4, 6:
length = int64(binary.BigEndian.Uint16(format[2:4]))
break
case 8, 10, 12, 13:
length = int64(binary.BigEndian.Uint32(format[4:8]))
break
case 14:
length = int64(binary.BigEndian.Uint32(format[2:6]))
break
default:
return nil
}
sr := io.NewSectionReader(r, offset, length)
t.Subtable[i] = CmapSubtable{pid, eid, &SubtableReader{sr}}
}
return Table(t)
}
// hashCore hashes a SectionReader using the ImoHash parameters.
func (imo *ImoHash) hashCore(f *io.SectionReader) [Size]byte {
var result [Size]byte
imo.hasher.Reset()
if f.Size() < int64(imo.sampleThreshold) || imo.sampleSize < 1 {
buffer := make([]byte, f.Size())
f.Read(buffer)
imo.hasher.Write(buffer)
} else {
buffer := make([]byte, imo.sampleSize)
f.Read(buffer)
imo.hasher.Write(buffer)
f.Seek(f.Size()/2, 0)
f.Read(buffer)
imo.hasher.Write(buffer)
f.Seek(int64(-imo.sampleSize), 2)
f.Read(buffer)
imo.hasher.Write(buffer)
}
hash := imo.hasher.Sum(nil)
binary.PutUvarint(hash, uint64(f.Size()))
copy(result[:], hash)
return result
}
